The subject matter disclosed herein relates to X-ray imaging systems, such as medical and industrial X-ray computed tomography (CT) imaging systems.
In modern medicine, medical professionals routinely conduct patient imaging examinations to assess the internal tissue of a patient in a non-invasive manner. Furthermore, for industrial applications related to security or quality control, screeners may desire to non-invasively assess the contents of a container (e.g., a package or a piece of luggage) or the internal structure of a manufactured part. Accordingly, for medical, security, and industrial applications, X-ray imaging, such as X-ray computed tomography (CT) imaging, may be useful for noninvasively characterizing the internal composition of a subject of interest.
For medical, security, and industrial computed tomography (CT) imaging, some resulting images may largely be a representation of the average density of each analyzed voxel, based on the attenuation of X-rays between the X-ray source and the X-ray detector by the subject undergoing imaging. However, for energy-sensitive or multi-energy X-ray imaging, a greater amount of imaging data may be gleaned for each voxel (e.g., the effective atomic number). Further, to reconstruct multi-energy CT projection data, the underlying physical effects of the interaction of the X-rays with the subject of interest may be discerned, namely, the scattering effects and photoelectric effects, in a process known as material decomposition. Material decomposition generally involves the construction of a mathematical model of X-ray attenuation characteristics such that any material in the subject of interest is composed entirely of two or more basis materials (e.g., water and iodine). By performing material decomposition on the acquired projection data, an image, such as a basis material density image or an effective atomic number image, may be constructed based on the model.